Homeomorphy in Recent Deep-Sea Brachiopods

Abstract

A collection of brachiopods from the Baja California Abyssal Plain forms a deep-sea assemblage unusual in that it contains three genera that are unrelated but externally almost identical; i.e., they are homeomorphs. One is Neorhynchia, an impunctate rhynchonellid; the second, a punctate terebratulid with short loop, is called Abyssothyris; and the third is referred to a new genus, Notorygmia, related to Macandrevia. A discussion of homeomorphy is followed by the systematics of the genera and species involved.